Most modern rail locomotives are of the diesel-electric variety, in which an internal combustion engine, most often a diesel engine, drives an electrical generator whose output provides power to traction motors to turn the wheels of the locomotive to generate motion. The diesel engine, which is typically a turbocharged diesel engine, requires a cooling system to limit the temperatures of various engine components. Accordingly, internal combustion engines are known to be designed with internal cooling passages for the circulation of coolant to remove heat energy from the engine components and from lubricating oil which is also circulated throughout the engine to reduce friction.
Similarly, other off-highway vehicles (“OHVs”), such as those used in the mining industry, may employ electrically motorized wheels for propelling or retarding the vehicle. For example, mining dump trucks typically include a large horsepower diesel engine (or other engine) in conjunction with an alternator, a main traction inverter, and a pair of wheel drive assemblies housed within the rear tires of the vehicle. The diesel engine is directly associated with the alternator such that the diesel engine drives the alternator. The alternator powers the main traction inverter, in which semiconductor power switches commutate the alternator output current to provide electrical power to electric drive motors of the two wheel drive assemblies.
Accordingly, rail vehicles and other OHVs may contain power electronics which are utilized to control and manage the conversion of mechanical energy into electrical energy and to control the supply of electrical power to the traction motors of the locomotive, other rail vehicle, or other OHV. These power electronics also require cooling systems to maximize lifespan and to ensure proper operation thereof.
Existing locomotives and other OHVs are, therefore, typically outfitted with an engine cooling system having an engine-dedicated liquid-to-air heat exchanger, e.g., a main radiator having an associated cooling fan, and a pump for circulating a cooling fluid through the engine and the main radiator. In addition, a separate cooling system is utilized for the power electronics. This separate cooling system includes a power electronics-dedicated liquid-to-air heat exchanger, e.g., a radiator having an associated cooling fan, and a pump for circulating a cooling fluid through the power electronics and the radiator.
As will be readily appreciated, however, having two separate cooling loops, each with a dedicated radiator and cooling fan, adds significant weight, volume and cost to the cooling system, as a whole.